Typically, multi-passenger buses and other vehicles are constructed of a chassis onto which a frame, often made of metal such as steel, is built. Attached onto the frame are exterior panels, which are often aluminum or fiberglass. Interior panels are attached to the frame to form the interior of the vehicle.
Multi-passenger vehicles, since they carry passengers that often do not wear restraints such as seatbelts, are subject to rigorous safety and crash test standards. However, since the frame is rigid and the panels are made of malleable, brittle materials, a crash or rollover of the vehicle results in the panels and frame deforming and/or breaking, causing serious injury to passengers. This results in a limited residual space (i.e., a survival zone for passengers) within the passenger compartment of the bus or vehicle.
Reinforcement measures have been implemented to increase the structural integrity of present frames and panels. For example, steel plates or other heavy, durable materials are appended to the frame and/or panels to increase their structural integrity.
Moreover, sandwich type panel constructions have also been used, such as to build recreational vehicles. These include a sandwich panel core material such as polystyrene, paper, metal honeycomb, foamed polyurethane, plywood, or fibrous boards. A sandwich panel facing material (such as steel, aluminum, plywood, hardboard, or fiberglass-reinforced plastic) is then bonded to the core materials and any reinforcing member. Another sandwich panel facing material may also be bonded to the core materials on the opposite side as the sandwich panel facing material. A support member can then be secured using a fastener to an outside of the sandwich panel at the reinforcing member.
However, these reinforcement techniques (i.e., steel plates and sandwich type panels) cause the multi-passenger vehicles to become excessively heavy, creating issues regarding Gross Vehicle Weight. Moreover, known sandwich type panels often insufficiently provide structural support to the vehicle, thereby still resulting in deformation and breakage upon impact during a crash, roll-over, etc.